autopsy of cetaceans, 2002/03...island (n = 2). the beachcast carcasses ranged from freshly dead to...

Autopsy of cetaceans includingthose incidentally caught incommercial fisheries, 2002/03

Pádraig J. Duignan and Gareth W. Jones

DOC SCIENCE INTERNAL SERIES 195

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© Copyright January 2005, New Zealand Department of Conservation

ISSN 1175�6519

ISBN 0�478�22645�4

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Mackenzie. Publication was approved by the Chief Scientist (Research, Development & Improvement

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CONTENTS

Abstract 5

1. Introduction 6

2. Materials and methods 7

2.1 Materials 7

2.2 Methods and necropsy protocol 8

2.2.1 Necropsy protocol 8

2.2.2 Stomach contents 9

2.2.3 Age determination 9

2.2.4 Reproductive status 10

3. Results 11

3.1 Morphometrics 11

3.2 Stomach contents 11

3.3 Age determination 11

3.4 Reproductive status 14

3.5 Pathology 16

4. Discussion 18

5. Acknowledgements 20

6. References 21

5DOC Science Internal Series 195

Autopsy of cetaceans includingthose incidentally caught incommercial fisheries, 2002/03

Pádraig J. Duignan and Gareth W. Jones

New Zealand Wildlife Health Centre, Institute of Veterinary,

Animal and Biomedical Sciences, Massey University,

Private Bag 11�222, Palmerston North, New Zealand

A B S T R A C T

Morphological characteristics, estimated age, gender, reproductive status,

stomach contents and cause of death have been determined for 11 Hector�s

dolphins (Cephalorhynchus hectori hectori), one Maui�s dolphin

(Cephalorhynchus hectori maui), four common dolphins (Delphinus delphis),

and one bottlenose dolphin (Tursiops truncatus). The common dolphins and

one Hector�s dolphin were killed incidentally in commercial fishing operations.

The remaining Hector�s dolphins and the Maui�s dolphin were retrieved either

from set-nets (n = 1), or found beachcast along the west coast of the North

Island (n = 1), west coast of the South Island (n = 7), or east coast of the South

Island (n = 2). The beachcast carcasses ranged from freshly dead to skeletal

remains. The stomachs of five Hector�s dolphins had detectable remains

consisting of fish, otoliths, and fish bones. Fish and squid were equally

represented in the stomachs of the common dolphins. Age was estimated by

counting dentinal growth layer groups in stained sections of teeth. Two female

Hector�s dolphins were too decomposed to determine reproductive status but

the remaining two were immature. Of five male Hector�s dolphins, one was

pubertal, three immature, and one was too decomposed for examination of

gonads. The male Maui�s dolphin and the bottlenose dolphin were also

immature. Of the four common dolphins, two Hector�s dolphins, and the

bottlenose dolphin known to have been net-entangled, all had lesions

consistent with death from asphyxiation. Two of the nine beachcast Hector�s

dolphins had lesions indicative of entanglement, two did not appear to have

been entangled and parasitic pneumonia may have had a role in their death, one

died from acute blunt trauma of unknown origin, and four were too

decomposed to determine cause of death. The Maui�s dolphin died from

complications associated with Aspergillus fumigatus infection of the lungs.

Keywords: autopsy, morphology, Hector�s dolphin, Cephalorhynchus hectori

hectori, Maui�s dolphin, Cephalorhynchus hectori maui, common dolphins,

Delphinus delphis, bottlenose dolphin, Tursiops truncatus, New Zealand

© January 2005, New Zealand Department of Conservation. This paper may be cited as:

Duignan, P.J.; Jones, G.W. 2005: Autopsy of cetaceans including those incidentally caught in

commercial fisheries, 2002/03. DOC Science Internal Series 195. Department of

Conservation, Wellington. 22 p.

6 Duignan & Jones�Autopsy of cetaceans, 2002/03

1. Introduction

The objective of this study was to fulfil the requirements of DOC contract CSL00/

3025 by recording and interpreting data on cetaceans submitted for autopsy.

These data included species, sex, size, body condition, age, reproductive status,

stomach contents, and cause of death. This report details the findings pertinent

to this objective and includes data on 11 Hector�s dolphins (Cephalorhynchus

hectori hectori), one Maui�s dolphin (Cephalorhynchus hectori maui), four

common dolphins (Delphinus delphis), and one bottlenose dolphin (Tursiops

truncatus) killed incidentally in fishing operations or found beachcast.

The Hector�s dolphin (Cephalorhynchus hectori) is a small coastal species and

New Zealand�s only endemic cetacean (Baker 1978). The species is divided

between at least four genetically distinct sub-populations, with a South Island

population of approximately 7300 individuals, and a North Island population

with fewer than 100 individuals (Ferreira & Roberts 2003). The North Island

population is genetically and morphologically distinct and is now called Maui�s

dolphin (Pichler et al. 1998; Baker et al. 2002). The South Island population has

a NZ threat classification of nationally vulnerable, while the North Island

population is listed as nationally critical. The life history characteristics of the

species are similar to other members of the genus Cephalorhynchus, such as

Commerson�s dolphin (C. commersoni) and are characterised by a low

potential for population growth (Lockyer et al. 1988; Slooten & Lad 1990). This,

combined with a low rate of female dispersal between populations, increases

the vulnerability of the species to local extinction if mortality rates exceed

recruitment. Entanglement appears to be one of the most significant factors

negatively impacting the species and was the impetus for establishment of a

Marine Mammal Sanctuary around Banks Peninsula in November 1988 (Dawson

& Slooten 1992) and in the Manukau Harbour and adjacent coast of the north-

western North Island in October 2003. Each year, particularly during the

summer months November to March, Hector�s and Maui�s dolphins are found

beachcast or incidentally caught in the inshore set-net gill fishery. Life history

parameters and cause of death have been reported for animals submitted for

autopsy between 1997 and 2001 (Duignan et al. 2003) and for the 2001/02

season (Duignan et al. 2004). This report includes similar data collected on

animals submitted during 2002/03.

The common dolphin (Delphinus delphis) is a pelagic, offshore species and has

a very wide distribution, occurring in all warm-temperate, subtropical, and

tropical waters worldwide (Leatherwood et al. 1983). In New Zealand, it is

frequently found in the coastal waters of both the North and South Islands

(Baker 1999). Group sizes vary seasonally and diurnally, but D. delphis are

regularly found in groups of several hundred, and sometimes of more than a

thousand, individuals (Leatherwood et al. 1983). The causes of mortality for

common dolphins include stranding (usually of single animals), entanglement,

and capture in direct-drive fisheries (Leatherwood et al. 1983).

The bottlenose dolphin (Tursiops truncatus) is known from warm and temper-

ate waters worldwide, is most common inshore, even entering rivers and estuar-


ies, and is rarely seen in the open ocean. However, they have been reported up

to 800 km from the nearest land (Watson 1981). In New Zealand they are most

common in the Marlborough Sounds, Bay of Plenty, Hauraki Gulf and Northland

(Baker 1999). There is an isolated population resident in Doubtful Sound in

Fiordland and this appears to be the southern limit for this species in New Zea-

land. The bottlenose dolphin included in this report is the first submitted to

Massey University for autopsy with a history of net entanglement.

2. Materials and methods

2 . 1 M A T E R I A L S

A total of 17 dolphins were submitted for autopsy. Most of the dolphins were

shipped frozen and wrapped in plastic and woven nylon body bags. Two ani-

mals (H61/02 and H70/03) were submitted chilled, but unfrozen. In most cases

the carcass was tagged with a CSL or DOC tag and accompanied by a data sheet.

Animals untagged are indicated in Tables 1 and 2. The four common dolphins

included three males and one female. The catch co-ordinates were reported for

the male dolphins, but not for the female although the capture date and name of

the vessel (not shown) were included on the CSL data sheet provided (Table 1).

The bottlenose dolphin was found beachcast on the Coromandel Peninsula, but

came ashore entangled in fishing gear. The latter was sent directly to CSL for

analysis by the DOC personnel who found the carcass.

The four female Hector�s dolphins were all from the west coast South Island

population. All were found beachcast between August and November 2002

(Table 2). Of the five male Hector�s, four were from the east coast and one from

Westport. Two of the east coast animals were retrieved from nets. H62/02 was

caught in a gill net set for rig north of Potato Point, Blueskin Bay, Otago

(Table 2). The second (WB03-07Chh) was entangled in a set net off South Bay,

Kaikoura, in February 2003 (Table 2). The remaining animals were beachcast.

TABLE 1 . CAPTURE DATA FOR CETACEANS, 2002/03.

CODE PATHOLOGY CSL DATE LATI- LONGI- SEX

NO. NO. (d/m/y) TUDE TUDE

Common dolphin Delphinus delphis

WB03-02Dd 33982 NT 1 Oct 02 ND ND F

WB03-04Dd 34086 84 17 Oct 02 39° 53′S 173° 41′E M

WB03-17Dd 34705 1026 30 Apr 03 40° 21′S 170° 00′E M

WB03-18Dd 34712 1028 30 Apr 03 40° 21′S 170° 00′E M

Bottlenose dolphin Tursiops truncatus

WB03-40Tt 35153 NT 5 Sep 03 Beachcast (ND) M

NT = not tagged. ND = no data provided.


Two Hector�s dolphins were too decomposed to determine their gender. Both

were found beachcast on the west coast in May 2003 (Table 2).

Only one Maui�s dolphin was autopsied. It was a male animal and it was found

beachcast in June 2003 at O�Neils Beach on the Auckland west coast (Table 2).

TABLE 2 . CAPTURE/REPORTING DATA FOR BEACHCAST AND BYCAUGHT Cephalorhynchus sp . , 2002/03.

CODE PATHOLOGY DOC DATE CIRCUMSTANCES LOCATION

NO. TAG NO. (d/m/y)

Hector�s dolphin�Female

WB03-01Chh 33976 H58/02 07 Oct 02 Beachcast Barrytown Beach, Punakaiki

WB03-05Chh 34363 H60 25 Nov 02 Beachcast Westport

WB03-06Chh 34371 H56/02 14 Aug 02 Beachcast Pororari Beach Spit, Punakaiki

WB03-10Chh 34462 H59/02 10 Nov 02 Beachcast Farewell Spit, Golden Bay

Hector�s dolphin�Male

WB03-03Chh 34209 H61 17 Dec 02 Beachcast Timaru

WB03-07Chh 34399 07 Feb 03 Entangled in net South Bay Kaikoura, reef 40m offshore

WB03-08Chh 34400 11 Dec 02 Beachcast Kaikoura, 200m S of Otumatu Rock

WB03-11Chh 34463 H62/02 20 Dec 02 Bycatch Blueskin Bay, Otago, 45 42S, 170 38E

WB03-27Chh 34851 H63/02 22 Dec 02 Beachcast North Beach, Westport (near set-net)

Hector�s dolphin�Gender unknown

WB03-16Chh 34679 H69/03 04 May 03 Beachcast Blaketown Beach, Greymouth

WB03-28Chh 34854 H68/03 02 May 03 Beachcast North Beach, 2km south of Orowaiti River

Maui�s dolphin�Male

WB03-19Chm 34780 H70/03 04 Jun 03 Beachcast O�Neils Beach, West Coast, Auckland

2 . 2 M E T H O D S A N D N E C R O P S Y P R O T O C O L

2.2.1 Necropsy protocol

Pathological examination and sampling was conducted according to a standard

protocol adapted from published small cetacean necropsy protocols (Geraci &

Lounsbury 1993; Jefferson et al. 1994). The procedure included recording the

body weight (kg), external measurements (m), and examination of the carcass

for external lesions such as trauma, net marks, tissue loss, scars, etc. Carcasses

were placed with the left side down and an incision made through the blubber

from the cranial insertion of the dorsal fin to the ventral midline. Blubber depth

(mm) was measured dorsally, laterally and ventrally along this incision. Then

the carcass was carefully flensed and the subcutis examined for evidence of

trauma.

Lesions in the blubber and subcutis were sampled for histopathology by fixing

tissue in 10% buffered formalin. A blubber sample was taken, where appropriate

due to state of decomposition, and stored at �20°C for future fatty acid analysis.

The internal organs were examined systematically for lesions and tissues

sampled for histopathology, virology (only if fresh), parasitology, bacteriology


(faeces routinely sampled but tissues only where appropriate), toxicology

(blubber), genetics (skin), and anatomical studies (skeleton or skull if requested

by Te Papa). The stomach was removed, tied off, and stored chilled until the

contents could be examined the same or following day. At least three of the

largest teeth from the middle of the dental arcade of the mandible were

extracted, washed and stored in 70% ethanol until they were prepared for age

determination. The reproductive organs were carefully dissected, measured

(mm), weighed (g), and stored in 10% buffered formalin. Any pathology found

was photographed.

2.2.2 Stomach contents

The full stomachs were weighed (kg), then opened with scissors and all

material washed into a 1 mm sieve. The stomach was then re-weighed to allow

the weight of the stomach contents to be determined. Large, relatively

undigested material was removed at this stage, and if possible an axial length

(mm) was measured for fish and squid. Smaller, more digested material was

gradually sorted using a black-bottomed tray. Otoliths were clearly visible

against this background, and as they are denser than most of the other material,

they sank to the bottom of the tray. Otoliths, squid beaks and other relevant

food material was also removed and stored in 70% ethanol. Parasites were

collected and preserved in 5% buffered formalin. Lesions in the gastric mucosa

were described, counted, and examples photographed.

2.2.3 Age determination

Age determination was based on a modification of a published protocol for

Hector�s dolphins (Slooten 1991). Briefly, the teeth were weighed (g) using a

Mettler PM 4800 Delta Range balance, and the length and greatest diameter

(mm) measured using Vernier callipers. The teeth were then washed in tap

water and decalcified for 24 hours in 5% nitric acid using at least 100 mL per

gram of tooth. After an overnight soak in water, the teeth were immersed in

formol formic acid for 24 hours and then washed overnight in running tap

water. The teeth were then soft enough to cut approximately one-third away

using a microtome blade. The cut surface was placed face down in a plastic

cassette and embedded in paraffin wax. The cassettes were processed by a

Citadel Tissue Processor (Shandon, UK) as for soft tissues. Sections were cut at

10�20 µm intervals using a microtome (Microtek Cut 4055F) and stainless steel

disposable microtome blades (S35 Feather Safe Razor Co. Medical Division,

Japan). Multiple sections were cut through each tooth and at least two teeth

were processed per animal. The sections were stained with toluene blue,

washed in water, dehydrated in absolute alcohol, cleaned in xylene, and

mounted on glass slides using rapid mounting medium. The tooth sections were

read independently by two observers at 16�80× magnification and the number

of dentinal growth layer groups (GLGs) assigned by consensus between the

readers.


2.2.4 Reproductive status

Females

Reproductive tracts were dissected out and examined grossly. The uterine

horns were opened and examined for signs of pregnancy. A sample of each horn

was removed, fixed in 10% buffered formalin, embedded in paraffin, sectioned

at 4 µm intervals, and stained with hematoxylin for microscopic examination as

per Lockyer & Smellie (1985) and Bacha & Wood (1990). The length and

diameter of the ovaries were measured (mm) using Vernier callipers, and the

ovaries weighed (g) using a Mettler PM 4800 Delta Range balance. The ovaries

were sliced at 2 mm intervals along their long axis with a scalpel. The slices

were examined for the presence of corpora lutea (CL) and corpora albicantia

(CA), both macroscopically and using a dissecting microscope at 10×

magnification. Sections were processed for microscopic examination as

described above. Sexual maturity was defined as the age at which a female had

ovulated at least once, and established by the presence of at least one corpus in

the ovaries (Harrison et al. 1972). The CAs were classified as per Marsh &

Kasuya (1984) and Slooten (1991).

Males

The length and midline diameter of the testes (excluding epididymis) were

measured (mm) using Vernier callipers and weighed (g) using a Mettler PM

4800 Delta Range balance. The epididymis was weighed (g) separately. Testes

were sectioned at 3 mm intervals using a scalpel and examined for evidence of

pathological changes. Histological samples taken from the centre of the testis

and epididymis, were embedded in paraffin wax, sectioned at 4 mm intervals,

mounted on glass slides and stained with haematoxylin and eosin. The sections

were then examined microscopically at 16�80× magnification to assess the

maturity of the seminiferous tubule epithelium and for the presence of

spermatozoa. Because the cell associations forming the epithelium vary

segmentally in mammalian testes, the predominant association in the section

was used to classify the stage of maturity. The gonads were classified as

immature, pubertal, mature-inactive, or mature-active (Collet & Saint Girons

1984; Slooten 1991).

Immature The seminiferous tubules/cords were narrow and often had no

apparent lumen. Sertoli cells and spermatogonia lined the tubules but no

further differentiation of germinal cells was apparent. There were abundant

interstitial cells. The duct of the epididymis was lined by simple cuboidal

epithelium and had a completely empty lumen.

Pubertal The seminiferous tubules were larger than for immature animals and

there was consequently less interstitial tissue. The epithelium of the tubules

contained spermatogonia, spermatocytes and occasional spermatids, but no

spermatozoa.

Mature-inactive The seminiferous tubules occupied most of the cross-

sectional area and had a defined lumen. The epithelium had sertoli cells,

spermatogonia, spermatocytes and early spermatids. Occasional tubule sections

may have contained late spermatids. The interstitial cells occupied very little

space between the seminiferous tubules. The ducts of the epididymis did not

contain spermatozoa.


Mature-active The majority of tubule sections in the testis were lined by an

epithelium that has a sequence of differentiation from spermatogonia through

to spermatozoa. There was relatively little interstitial tissue present. The lumen

of the epididymis might be full of spermatozoa.

3. Results

3 . 1 M O R P H O M E T R I C S

An extensive set of standard measurements was taken where possible given the

state of decomposition of each carcass (Table 3).

3 . 2 S T O M A C H C O N T E N T S

The stomach weight and the weight of the contents were recorded for each

animal where possible (Table 4). The contents were not identifiable to species

for any animal but further work on materials collected will be conducted by

Kirsty Russell, Auckland University. Only four Hector�s dolphins had contents

in at least one stomach compartment. Most of these contents were indigestible

remains of teleost fish such as bones, eye lenses and otoliths, and an occasional

squid beak. Incidentally the two known bycatch Hector�s dolphins had the most

undigested remains. The dolphin caught in Blueskin Bay had an undigested fish

in its stomach while the dolphin caught in Kaikoura had fish bones as well as

otoliths. Two dolphins had no stomachs due to scavenging and decomposition.

The Maui�s dolphin had also eaten relatively recently and intact fish,

invertebrates, bones and otoliths were found in both the first and second

chambers of the stomach.

The male common dolphins had evidence of recent feeding with a range of food

items in the stomachs including intact fish, otoliths, bones and squid, squid

mantles, and squid beaks. The female dolphin had an empty stomach (Table 4).

The bottlenose dolphin had been entangled for some time and was severely

emaciated. The only material found in its stomach was plant debris.

3 . 3 A G E D E T E R M I N A T I O N

Data on tooth size and the number of dentinal growth layer groups (GLGs)

counted are given in Table 5. Because of technical problems with the sectioning

equipment the sections obtained from some teeth (asterisks on Table 5) were

not of high enough quality to determine the age with certainty. A second tooth

sample from each of these animals is being processed at the time of writing, and

the results will be included in an amended report. For the Hector�s dolphins

with teeth (n = 11) the mean tooth weight and size was similar to that reported

previously (Slooten 1991; Duignan et al. 2003). The teeth did not have obvious

incremental layers in the cementum, but there were clearly defined bands in the


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dentine of most animals. The accepted protocol for small cetaceans is that one

dark band (stained) and one light band (unstained) constitute one year�s growth

(Perrin & Myrick 1980; Slooten 1991). Based on this assumption, the Hector�s

dolphins ranged in age from one and a half years to 15 years old.

The common dolphins ranged from animals three or four years old to one male

that was eight years old. The bottlenose dolphin is one of the animals for which

a second tooth is being sectioned.

3 . 4 R E P R O D U C T I V E S T A T U S

Females

Morphometric data on reproductive tracts are given in Table 6. Hector�s

dolphin WB03-06Chh (H56/02) was badly decomposed with loss of much of the

genital area and mammary glands. The ovaries were present, however they were

inactive, without evidence of ovulation or corpora (Table 6). The reproductive

tract and mammary glands of WB03-10Chh (H59/02) were immature. These

findings are similar to those for female Hector�s dolphins, 6 years and younger,

reported by Slooten (1991) and also consistent with those of immature female

TABLE 5 . AGE ESTIMATION BASED ON DENTINAL GROWTH LAYER GROUPS (GLG)

FOR CETACEANS, 2002/03.

CODE PATH- CSLTOOTH

OLOGY CODE WEIGHT LENGTH WIDTH DEPTH GLGs

NO. (g) (mm) (mm) (mm)

Hector�s dolphin

WB03-01Chh 33976 H58/02 0.13 14 2.8 2.6 10

WB03-03Chh 34209 H61/02 0.06 7.8 1.8 1.7 1.5

WB03-05Chh 34363 H60/02 0.11 12.3 2.5 2.6 13

WB03-06Chh 34371 H56/02 0.11 9.3 3.1 2.7 15

WB03-07Chh 34399 0.12 12.7 2.5 2.6 9

WB03-08Chh 34400 0.12 12.6 2.7 2.7 5

WB03-10Chh 34462 H59/02 0.1 11.9 2.5 2.3 5

WB03-11Chh 34463 H62/02 0.09 12.4 2.6 2.5 1.5

WB03-16Chh 34679 H69/02 0.06 7.8 1.8 1.7 12

WB03-27Chh 34851 H63/02 0.1 12.2 2.8 2.9 3

WB03-28Chh 34854 H68/03 0.12 12 3.2 2.8 6*

Maui�s dolphin

WB03-19Chm 34780 H70/03 0.12 12.3 3 2.9 *

Common dolphin

WB03-02Dd 33982 0.15 13.7 3.6 3.2 4

WB03-04Dd 34086 84 0.16 14.4 3 3.6 *

WB03-17Dd 34705 1026 0.15 16.2 3.5 3.1 3 to 4*

WB03-18Dd 34712 1028 0.16 14.5 3.7 3 8

Bottlenose dolphin

WB03-40Tt 35153 0.6 21.7 7.3 7 *

* To be re-cut and read due to poor quality of tooth sections.


dolphins, 5 years or younger, from previous bycatch reports (Duignan et al.

2003, 2004). The gonads of three dolphins (H58/02 and H60/02) had been

scavenged or decomposed and were not available for examination.

The common dolphin had a 13 mm corpus albicans in the left ovary but the

uterus was not well developed and milk was not present in the mammary

glands. This dolphin was estimated to be four years old and may be at the end of

puberty and showing the first evidence of ovarian activity.

Males

The gonads were examined for four male Hector�s dolphins and one Maui�s dol-

phin. Of these, one animal (WB03-07Chh) had testes with histological features

consistent with transition from puberty to maturity. The summed testicular

weight of 198 g is below the range previously found for fully mature combined

testicular mass (266 g�1210 g) as reported by Slooten (1991) and Duignan et al.

(2003), but similar to that of a mature-inactive male that had a combined testicu-

lar mass of 185 g (Duignan et al. 2003). Although the gradation between imma-

ture, pubertal and mature is probably indistinct, pubescent males would be ex-

pected to have an intermediate combined testicular mass. The remaining dol-

phins were definitely immature with summed testicular mass ranging from 21 g

to 30 g. In previous studies the combined testicular mass for the gonads of im-

mature dolphins ranged from 10.9 g to 29.6 g (Duignan et al. 2003, 2004).

Of the three male common dolphins, one (WB03-04Dd) was sexually mature

with active spermatogenesis and summed testicular mass of 1078 g. This

dolphin was also of mature body size at 2.06 m standard length. Active gonads

are consistent with its capture date in mid October as most reproductive

activity for this species occurs in spring and summer (Watson 1981;

Leatherwood et al. 1983). The two remaining dolphins were shorter in body

length and had markedly smaller testes at 56 g and 66 g summed mass

respectively. The gonads were mature but inactive and consistent with their

time of death in the autumn as both were caught on 30 April. The bottlenose

dolphin had an immature reproductive tract (Table 7).

TABLE 6 . FEMALE REPRODUCTIVE TRACT MORPHOMETRICS AND CHARACTERISTICS , 2002/03.

PATH-RIGHT OVARY LEFT OVARY

CODE OLOGY WT L×W×D CA CL WT L×W×D CA CL GRAVID MILK

NO. (g) (mm) (g) (mm) (Y/N) (Y/N)

Hector�s dolphin

WB03-01Chh 33976 � scavenged � � � � � � � �

WB03-05Chh 34363 � scavenged � � � � � � � �

WB03-06Chh 34371 1 27×12×7 1 27×12×10 N N

WB03-10Chh 34462 0.5 22×10×2 � � 0.7 25×10×4 � � N N

Common dolphin

WB03-02Dd 33982 2 30×14×14 � � 4.9 39×21×18 13 mm � N N

diameter

CA = Corpus albicans. CL = Corpus luteum.


TABLE 7 . MALE REPRODUCTIVE MORPHOMETRICS AND CHARACTERISTICS , 2002/03.

PATH-RIGHT TESTIS LEFT TESTIS

SUMMED

CODE OLOGY WT+EPID WT�EPID L×W×D WT+EPID WT�EPID L×DIAMETER TESTICULAR

NO. (g) (g) (mm) (g) (g) (mm) WT (g)

Hector�s dolphin

WB03-03Chh* 34209 � � � � � � �

WB03-07Chh 34399 94 74 129×28 104 89 106×30 198

WB03-08Chh 34400 13 9 70×19 17 12 81×19 30

WB03-11Chh 34463 8 6 49×12 9 7 56×13 17

WB03-27Chh 34851 11 7 53×15 10 7 54×14 21

Maui�s dolphin

WB03-19Chm 34780 52 39 105×30×21 52 38 99×32×27 104

Common dolphin

WB03-04Dd 34086 568.0 517.0 263×60 510.0 478.0 270×59 1078.0

WB03-17Dd 34705 29.0 22.0 85×19 27.0 20.0 85×22 56.0

WB03-18Dd 34712 34.1 19.1 103×22 32.2 28.7 105×21 66.3

Bottlenose dolphin

WB03-40Tt 35153 5 4 48×9 6 3 55×11 11

* Gonads decomposed.

3 . 5 P A T H O L O G Y

Entanglement-related pathology is included in Table 8. It should be noted that

freezing can compromise the interpretation of subtle pathological changes and

make the determination of cause of death difficult.

Of the four female Hector�s dolphins, only one (H59/02) showed clear evidence

of having died as a result of fishing operations. This animal had net marks on its

skin, subcutaneous trauma, and respiratory congestion and oedema

characteristic of asphyxiation. This animal had been found beachcast on

Farewell Spit. An incidental finding in this animal was lungworm infection. The

remaining females were either too autolysed to permit detection of possible

entanglement related pathology or had been badly scavenged. Thus, the

probability of their having been bycaught is unknown.

Five male Hector�s dolphins were examined. Two (H62/02 and WB03-07Chh)

were known to have died after entanglement in fishing gear and they had

epidermal and pulmonary pathology consistent with this. Both also had

evidence of blunt trauma. H63/02 had similar pathology although it was found

beachcast in Westport. Thus the probability of entanglement for this dolphin is

also high. WB03-08Chh and H61/02 are less likely to have died as a result of

fishing operations. Both had evidence of blunt trauma with the juvenile H61/02

having trauma to the head and neck that may have been the result of boat strike

or aggression from other dolphins, predator attack (killer whales), or trauma in

rough seas. WB03-08Chh had severe parasitic pneumonia that may have had a

role in its demise.


The juvenile male Maui�s dolphin died from natural causes with severe fungal

pneumonia caused by Aspergillus fumigatus infection.

All of the common dolphins were known bycatch. Their pathology is consistent

with this in that all have epidermal net marks, evidence of acute blunt trauma,

and acute pulmonary and tracheal congestion, oedema, and haemorrhage.

WB03-18Dd also had a fractured flipper.

The bottlenose dolphin was found beachcast with fishing gear entangled

around its rostrum and embedded in the gingival at the commisures of the

mouth. The latter, along with drag caused by the mass of gear, prevented

feeding and this animal was severely emaciated. Its ultimate cause of death was

respiratory failure as indicated by markedly congested and oedematous lungs.

TABLE 8 . PATHOLOGY OF CETACEANS, 2002/03.

PATH- DOCENTANGLEMENT-RELATED PATHOLOGY

CODE OLOGY CODE GROSS ENTANGLEMENT

NO. PROBABILITY

Hector�s dolphin�Female

WB03-01Chh* 33976 H58/02 Too autolysed Unknown

WB03-05Chh* 34363 H60/02 Unknown

WB03-06Chh* 34371 H56/02 7 Unknown

WB03-10Chh 34462 H59/02 1,3,5 High

Hector�s dolphin�Male

WB03-03Chh* 34209 H61/02 3 Low

WB03-07Chh 34399 1,3,5 High

WB03-08Chh 34400 1,3 Low

WB03-11Chh 34463 H62/02 1,3,5 High

WB03-27Chh 34851 H63/02 1,3,5 High

Hector�s dolphin�Gender unknown

WB03-16Chh* 34679 Too autolysed Unknown

WB03-28Chh* 34854 Too autolysed Unknown

Maui�s dolphin�Male

WB03-19Chm 34780 H70/03 1,2,3 Low

Common dolphin�Female

WB03-02Dd 33982 5 High

Common dolphin�Male

WB03-04Dd 34086 84 1,3,5 High

WB03-17Dd 34705 1026 1,3,5 High

WB03-18Dd 34712 1028 1,3,5,7 High

Bottlenose dolphin

WB03-40Tt 35153 1,5 High

LEGEND

1 = Respiratory congestion

and oedema

2 = Pulmonary emphysema

3 = Trauma (contusion +/�

free blood in abdomen)

4 = Foreign matter in lungs

5 = External net

entanglement marks

6 = Regurgitated food in

oesophagus

7 = Bone fractures

* = Marked decomposition


4. Discussion

The dolphins examined for this contract were received frozen and double

bagged. In general the packaging was of a high standard and the animals were

identified by CSL observer or Independent Fisheries Ltd data sheets, or by

orange tags attached around the tail-stock. The orange tags around the tail-stock

of Hector�s dolphins were very effective for animal identification. It was

beneficial having a list of animals being shipped forwarded by e-mail to allow a

cross check between animals shipped and those received. In that way, any

animal that arrived without a CSL tag or stranding form could be traced. From a

health and safety perspective the packaging was sufficient to prevent

contamination of the environment by the carcasses provided they are

maintained frozen. Two carcasses were submitted chilled but not frozen. This is

ideal for pathology and is recommended for animals originating on the North

Island where shipping chilled carcasses should be possible logistically. A

second originated in Timaru, but was transported personally by Al Hutt to avoid

having it frozen and to facilitate a speedy diagnosis.

The life history characteristics of the common dolphin are similar to those

examined in previous CSL contracts (Duignan et al. 2003, 2004), and in

previous studies (Leatherwood et al. 1983). The three male dolphins had not

attained full adult length and only the largest appears to have attained gonadal

maturity. The female common dolphin was the largest of the four common

dolphins submitted and she had attained gonadal maturity at four years. The

common dolphins were all caught as a result of commercial fishing activities

and had cutaneous, soft tissue, and pulmonary lesions suggestive of blunt

trauma, entanglement and asphyxiation.

The Hector�s dolphins caught by commercial or recreational nets and those

found beachcast were from areas of the west and east coasts of the South Island,

areas which have a high Hector�s dolphin population (Slooten & Dawson 1994;

Slooten et al. 2002). A single Maui�s dolphin from the west coast of the North

Island where a relict population occurs (Ferreira & Roberts 2003), was also

submitted for necropsy. Morphological features of these animals were

consistent with those reported previously for Cephalorhynchus hectori

(Mörzer-Bruyns & Baker 1973; Slooten 1991; Slooten & Dawson 1994). The life

history data collected from these dolphins complements data from 12 animals

examined in 1999, 16 examined in 2000, and 18 in 2001, and 10 from 2002

(Duignan et al. 2003, 2004). The sex ratio of dolphins submitted was equal, as

compared to a bias in previous years with males comprising 62% of the animals

submitted in 2001, 56% in 2000, and 83% in 1999. This male bias over the

previous three years differs from a female bias reported by Slooten (1991).

Whether the bias represents a population bias or a sampling artefact is

unknown. There was also a bias towards younger and immature animals as in

previous studies based on bycatch and beachcast animals (Slooten 1991;

Dawson 1991; Duignan et al. 2003, 2004).

Determination of the species of fish and invertebrates ingested by the dolphins

was beyond the scope of this investigation, but all hard parts removed from the


stomachs have been archived for future studies. As in previous years, the

stomach contents of Hector�s and Maui�s dolphins have been archived for Kirsty

Russell, Auckland University, for studies on foraging. Stomach contents of

Hector�s dolphins were similar to those examined by Duignan et al. (2003). The

remains predominately consisted of indigestible teleost fish bones and otoliths

and invertebrate carapaces. Fish predominated in the stomachs of Hector�s and

Maui�s dolphins, but fish and squid were equally represented in the stomach of

common dolphins. The bottlenose dolphin was so emaciated that there were no

recognizable food remains in its stomach.

The principle of age determination in cetaceans based on counting growth

layers or annuli in teeth is commonly used on a variety of species (Perrin &

Myrick 1980). Although widely used the technique is subject to difficulties in

methodology, interpretation, reader variability, variability among teeth, and the

lack of known age animals (Dapson 1980). The method used to section teeth

can also introduce marked biases into the interpretation of age. For consistency

with earlier studies this investigation employed a method previously used to age

Hector�s dolphins (Slooten 1991) that is based on paraffin embedding of

decalcified teeth followed by thin sectioning. It is a particularly difficult

method and inferior to methods used on other small cetaceans such as the

related Commerson�s dolphin (Lockyer et al. 1988). Consultation with Dr

Lockyer (Age Dynamics, Denmark) in August 2003, and future collaboration

with her in 2004, will probably see a revision of the methodology employed at

Massey especially in light of difficulties experienced with some teeth for this

study.

Entanglement in fishing gear may result in traumatic lesions immediately

apparent in the exterior of the carcass such as abrasions, amputations,

penetrating wounds and fracture of limb bones, mandibles or teeth (Kuiken

1994; Kuiken et al. 1994; Garcia Hartman et al. 1994). For cetaceans, diagnosis

of the aetiology is relatively simple because the sensitive hairless skin is easily

damaged and characteristic net marks are often left as impression marks around

the rostrum, melon and flippers or dorsal fin. Acute blunt trauma to the body

may result in contusions, haemorrhage, and skeletal fractures that are apparent

at necropsy. More specific are the cardio-pulmonary changes associated with

asphyxiation. These changes include diffuse pulmonary oedema, congestion,

emphysema, blood-stained froth in airways and pleural congestion. There may

also be congestion of pericardial vessels, ecchymotic haemorrhages on the

endocardium or epicardium; and on histology, hyper-contraction of myofibres

is seen along with fibre fragmentation and vacuolation (Lunt & Rose 1987).

Cutaneous lesions, characteristic of net marks, were observed on four Hector�s

dolphins, all of the common dolphins and the bottlenose dolphin. Three

Hector�s dolphins were too decomposed to definitely determine any skin

pathology and two appeared not to have net impressions on the skin. However,

net marks are not always evident on dolphins known to have been entangled

and there should be some caution in the interpretation of this finding (Duignan

et al. 2003).

Acute pulmonary lesions indicative of asphyxiation were present in both

Hector�s dolphins and in the bottlenose and common dolphins known to have

died as a result of capture in fishing gear. These lesions took the form of acute


diffuse congestion and oedema of the lungs, congestion and haemorrhage in the

airways, and blood-stained froth in the airways. These animals also appeared to

have acute subendocardial cardiomyopathy (hyper-contraction and fibre

fragmentation) of the thickest part of the left ventricular wall consistent with

coagulative myocytolysis or coagulative necrosis. Both lesions are

morphologically similar particularly in the peracute to acute stage of lesion

development. Generally cardiac lesions take hours to develop to a stage where

necrosis is unequivocal. In humans with myocardial infarction, necrosis is not

seen for up to twelve hours post infarction (Kumar et al. 1992). However

ultrastructural changes as determined by electron microscopy can be seen after

two hours. Electron microscopy cannot be carried out on pre-frozen tissue.

Thus too little time may elapse between the onset of a lesion in the dolphin

myocardium and the death of the animal. Freezing may also induce changes that

can be confused with true lesions. This problem can only be addressed by

conducting necropsies on fresh unfrozen dolphins as soon as possible after

death by entanglement.

Of the nine Hector�s dolphins that were beachcast, two (22%) have a high

probability, based on observed lesions, of having died as a result of

entanglement in fishing gear. One juvenile animal appears to have died

suddenly from blunt trauma, but the origin of that trauma could not be

determined. Two others had severe parasitic pneumonia and that may have

played a role in their death. The remaining four animals were too decomposed

to determine cause of death. The Maui�s dolphin died as a result of severe

pulmonary infection by the opportunistic terrestrial fungus, Aspergillus

fumigatus. In this case the fungus invaded the pulmonary artery from the lung

and caused intra thoracic haemorrhage that caused death. Aspergillosis is

extremely rare in dolphins worldwide, but has been reported in striped

dolphins, Stenella coeruleoalba, and bottlenose dolphins debilitated by

morbillivirus infection (Domingo et al. 1992; Lipscomb et al. 1994). A previous

case was reported for a juvenile male Hector�s dolphin with fulminating

pulmonary and cerebral aspergillosis (Duignan et al. 2003). In neither case was

morbillivirus implicated based on virus isolation and immunohistochemical

staining of tissues for morbillivirus antigen (Duignan et al. manuscript in

preparation). However, the underlying cause for immunosuppression in

Hector�s and Maui�s dolphins remains unresolved.

5. Acknowledgements

Carcasses were submitted by government observers (Ministry of Fisheries), Jim

Lilley (Marine Watch), and DOC staff: J. Fyfe, A. Hutt, M. Morrissey, K. McLeod,

S. Mowbray, D. Neale, H. Stoffregen, and C. Wood. Assistance with necropsies,

sorting and identifying stomach was provided on occasion by A. Castinel, F.

Sapriza, and M. Stratton. Pat Davey assisted with tooth sectioning and prepared

histological slides. Our thanks to the following: L. Rogers for bacteriology, B.

Adlington for parasitology, D. Knight for virology, Dr Christina Lockyer, Age


Dynamic, Denmark, for consultation on age determination. Wendy Graham

provided secretarial assistance. We acknowledge the goodwill of the

Department of Pathobiology and the Institute of Veterinary Animal and

Biomedical Sciences in provision of facilities, storage space, use of the chiller,

space for freezers. M. Hogan is particularly helpful in assisting with carcasses

and waste disposal. The research described in these reports was funded by DOC

(Science Investigation nos 96/3040 and 99/3025).

6. References

Bacha, W.J.; Wood, L.M. 1990. Color atlas of veterinary histology. Lea & Febiger, Philadelphia. Pp.

207�230.

Baker, A.N. 1978. The status of Hector�s dolphin, Cephalorhynchus hectori (van Beneden), in

New Zealand waters. Report of the International Whaling Commission 28: 331�334.

Baker, A.N. 1999. Whales and dolphins of New Zealand and Australia. Victoria University Press,

Wellington. 115 p.

Baker, A.N.; Smith, A.H. Pichler, F.B. 2002. Geographical variation in Hector�s dolphin:

recognition of new subspecies of Cephalorhynchus hectori. Journal of the Royal Society

of New Zealand 32 (4): 713�727.

Collet, A.; Saint Girons, H. 1984. Preliminary study of the male reproductive cycle in common

dolphins, Delphinus delphis, in the eastern North Atlantic. Report of the International

Whaling Commission, Special Issue 6: 355�360.

Dapson, R.D. 1980. Guidelines for statistical usage in age estimation techniques. Journal of

Wildlife Management 44: 541�548.

Dawson, S.M. 1991. Incidental catch of Hector�s dolphin in inshore gillnets. Marine Mammal

Science 7(3): 283�295.

Dawson, S.M.; Slooten, E. 1992. Conservation of Hector�s dolphins: a review of studies that led to

the establishment of the Bank�s Peninsula marine mammal Sanctuary. Canterbury

Conservancy Technical Report Series 4. Department of Conservation, Canterbury, New

Zealand.

Domingo, M.; Visa, J.; Pumarola, M.; Marco, A.J.; Ferrer, L.; Rabanal, R.; Kennedy, S. 1992.

Pathologic and immunocytochemical studies of morbillivirus infection in striped dolphins

(Stenella coeruleoalba). Veterinary Pathology 29: 1�10.

Duignan, P.J.; Gibbs, N.J.; Jones, G.W. 2003. Autopsy of cetaceans incidentally caught in fishing

operations 1997/98, 1999/2000, and 2000/01. DOC Science Internal Series 119. 66 p.

Duignan, P.J.; Gibbs, N.J.; Jones, G.W. 2004. Autopsy of cetaceans incidentally caught in

commercial fisheries, and all beachcast specimens of Hector�s dolphins, 2001/02. DOC

Science Internal Series 176. 28 p.

Ferreira, S.M.; Roberts, C.C. 2003. Distribution and abundance of Maui�s dolphins

(Cephalorhynchus hectori maui) along the North Island west cost, New Zealand. DOC

Science Internal Series 93: 19 p.

Garcia Hartmann, M.; Couperus, A.S.; Addink, M.J. 1994. The diagnosis of by-catch: preliminary

results of research in the Netherlands. European Cetacean Society Newsletter, Special

Issue 26: 16�26.

Geraci, J.R.; Lounsbury, V.J. 1993. Marine mammals ashore: A field guide for strandings. Texas

A&M Sea Grant Publications, Galveston. Pp. 175�228.


Harrison, R.J.; Brownell, R.L.; Boice R.C. 1972. Reproduction and gonadal appearances in some

odontocetes. Pp. 361�429 in Harrison, R.J. (Ed.) Functional anatomy of marine mammals.

vol. 1. Academic Press, London.

Jefferson, T.A.; Myrick, A.C.; Chivers, S.J. 1994. Small cetacean dissection and sampling: a field

guide. National Oceanic and Atmospheric Administration Technical Memorandum,

National Marine Fisheries Service�Southwest Fisheries Science Centre 198.

Kuiken, T. 1994. A review of the criteria for the diagnosis of by-catch in cetaceans. European

Cetacean Society Newsletter Special Issue 26: 38�43.

Kuiken, T.; Simpson, V.R.; Allchin, C.R.; Bennett, P.M.; Codd, G.A.; Harris, E.A.; Howes, G.J.;

Kennedy, S.; Kirkwood, J.K.; Law, R.J.; Merrett, N.R.; Philipps, S. 1994. Mass mortality of

common dolphins (Delphinus delphis) in south west England due to incidental capture in

fishing gear. The Veterinary Record 134: 81�89.

Kumar, V.; Cotran, R.S.; Robbins, S.L. (Eds) 1992. Basic pathology. 5th edition. W.B. Saunders,

Philadelphia. Pp. 308�313.

Leatherwood, S.; Reeves, R.R; Foster, L. 1983. The Sierra Club handbook of whales and dolphins.

Dai Nippon Printing, Tokyo, Japan. Pp. 200�203.

Lipscomb, T.P.; Schulman, F.Y.; Moffatt, D.; Kennedy, S. 1994. Morbilliviral disease in Atlantic

dolphins (Tursiops truncatus) from the 1987�1988 epizootic. Journal of Wildlife

Diseases 30: 567�571.

Lockyer, C.; Goodall, R.N.P.; Galeazzi, A.R. 1988. Age and body length characteristics of

Cephalorhynchus commersoni from incidentally caught specimens off Tierra del Fuego.

Reports of the International Whaling Commission, Special Issue 9: 103�118.

Lockyer, C.; Smellie, C.G. 1985. Assessment of reproductive status of female fin and sei whales

taken off Iceland, from a histological examination of the uterine mucosa. Reports of the

International Whaling Commission 35: 343�348.

Lunt, D.W.; Rose, A.G. 1987. Pathology of the human heart in drowning. Archives of Pathology

and Laboratory Medicine 111: 939�942.

Marsh, H.; Kasuya, T. 1984. Changes in ovaries of the short-finned pilot whale Globicephala

macrorhynchus, with age and reproductive activity. Reports of the International

Whaling Commission, Special Issue 6: 311�335.

Mörzer Bryuns, W.F.J.; Baker, A.N. 1973. Notes on Hector�s dolphins Cephalorhynchus hectori

(van Beneden) from New Zealand. Records of the Dominion Museum 8: 125�137.

Perrin, W.F.; Myrick, A.C. Jr. (Eds).1980. Age determination of toothed whales and sirenians.

Reports of the International Whaling Commission, Special Issue 3. 281 p.

Pichler, F.; Baker, C.S.; Dawson, S.M.; Slooten, E. 1998. Geographic isolation of Hector�s dolphin

populations described by mitochondrial DNA sequences. Conservation Biology 12: 676�

682.

Slooten, E. 1991. Age, growth and reproduction in Hector�s dolphins. Canadian Journal of

Zoology 69: 1689�1700.

Slooten, E.; Dawson, S.M. 1994. Hector�s dolphin Cephalorhynchus hectori (van Beneden, 1881).

Pp. 311�333 in Ridgway, S.H.; Harrison, R. (Eds) Handbook of marine mammals. vol. 5.

Academic Press, London.

Slooten, E.; Lad, F. 1990. Population biology and conservation of Hector�s dolphin. Canadian

Journal of Zoology 69:1701�1707.

Slooten, E.; Dawson, S.; Rayment, W. 2002. Quantifying abundance of Hector�s dolphins between

Farewell Spit and Milford Sound. DOC Science Internal Series 35. 18 p.

Watson, L. 1981. Sea guide to whales of the world. Hutchinson, London. Pp. 270�277.

autopsy of cetaceans, 2002/03...island (n = 2). the beachcast carcasses ranged from freshly dead to...

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